One of the issues I noticed with the long, long, long vegetarian discussions we've had at DW has to do with what counts as authoritative across Mahayana traditions. When practitioners discuss various topics with each other, certain assumptions about What Matters and What Is Of Value are made, which is problematic because the assumptions of one practitioner are likely not to align with another.

For example, one person argued that vegetarianism is necessary to Mahayana Buddhist practice upon the authority of the Surangama Sutra, and argued directly that meat-eating directly contravenes the teachings of Shakyamuni Buddha. That sutra is certainly authoritative for a Ch'an practitioner, but outside of China, it is not typically regarded as canonical, and therefore not authoritative. This was pointed out, and offense was taken. Meanwhile, another person pointed to a passage in the Hevajra Tantra in support of including meat in the diet of a practitioner as an act of compassion (rough paraphrase here). Is that tantra authoritative for all practitioners? No. But there was a sense among some that if you don't regard the texts and traditions I value as a final authority for your practice, then you are disrespecting the texts and traditions I value, and by extension, disrespecting me.

So: What is an authoritative text or source across Mahayana? I've been posing this question to myself as a way to avoid these kinds of difficulties in cross-Mahayana discourse. What's authoritative in this sub, and what is less authoritative or not at all authoritative?

I am entertaining the following hypothesis:

According to Mahayana Buddhism, the history of Mahayana Buddhist doctrine is a narrative and catalogue of decline. Innovations in the teachings are not improvements; they are signs of degeneration--they are the introduction and compounding of errors. This suggests that the canon of Mahayana texts recorded in Sanskrit, prior to the decline of Buddhism in India, must be more authoritative for the purposes of pan-Mahayana discussion than, say, later Chinese, Tibetan, Japanese, or Korean doctrinal systems. These texts have the further advantage of being shared in common among all Mahayana traditions in some manner, apropos of the recurring problem that emerged with the "vegetarian" discussions.

I'm not completely at ease with this idea, because it implies a poor attitude toward some traditions that I and others value highly, even though I arrived at it with the intention to promote sane and ultimately respectful discourse across traditions. I recognize that I may be running a fool's errand here, and I am probably a poor communicator most days.

One of the issues I noticed with the long, long, long vegetarian discussions we've had at DW has to do with what counts as authoritative across Mahayana traditions. When practitioners discuss various topics with each other, certain assumptions about What Matters and What Is Of Value are made, which is problematic because the assumptions of one practitioner are likely not to align with another.

For example, one person argued that vegetarianism is necessary to Mahayana Buddhist practice upon the authority of the Surangama Sutra, and argued directly that meat-eating directly contravenes the teachings of Shakyamuni Buddha. That sutra is certainly authoritative for a Ch'an practitioner, but outside of China, it is not typically regarded as canonical, and therefore not authoritative. This was pointed out, and offense was taken. Meanwhile, another person pointed to a passage in the Hevajra Tantra in support of including meat in the diet of a practitioner as an act of compassion (rough paraphrase here). Is that tantra authoritative for all practitioners? No. But there was a sense among some that if you don't regard the texts and traditions I value as a final authority for your practice, then you are disrespecting the texts and traditions I value, and by extension, disrespecting me.

So: What is an authoritative text or source across Mahayana? I've been posing this question to myself as a way to avoid these kinds of difficulties in cross-Mahayana discourse. What's authoritative in this sub, and what is less authoritative or not at all authoritative?

It's a genuine and unavoidable problem. Two broad categories of solutions come to mind:
(1) The common ground of all Mahayanists is (more or less) consensus reality/scientific rationalism. Basing arguments on that common ground detours around the problem.
(2) Restricting the conversation to ever-narrower groups. This, after all, is why we have the two Wheels, and the sub-forums on DWM.

I am entertaining the following hypothesis:

According to Mahayana Buddhism, the history of Mahayana Buddhist doctrine is a narrative and catalogue of decline. Innovations in the teachings are not improvements; they are signs of degeneration--they are the introduction and compounding of errors. This suggests that the canon of Mahayana texts recorded in Sanskrit, prior to the decline of Buddhism in India, must be more authoritative for the purposes of pan-Mahayana discussion than, say, later Chinese, Tibetan, Japanese, or Korean doctrinal systems. These texts have the further advantage of being shared in common among all Mahayana traditions in some manner, apropos of the recurring problem that emerged with the "vegetarian" discussions.

I'm not completely at ease with this idea, because it implies a poor attitude toward some traditions that I and others value highly, even though I arrived at it with the intention to promote sane and ultimately respectful discourse across traditions. I recognize that I may be running a fool's errand here, and I am probably a poor communicator most days.

Both teams played hard.

If we buy the theory that the "history of Mahayana Buddhist doctrine is a narrative and catalogue of decline", then your solution works well ... except that some Mahayana traditions barely know that the older texts exist.
My own way of thinking about the various schools of Buddhist thought is that they are all legitimate developments from the earliest teachings - honest efforts by good, smart people to extend Gautama's teachings and to make them relevant in new contexts.
Following your logic but from my starting point, I have to conclude that the canonical scriptures of all schools are equally authoritative.
For all of us.

It's a tightrope for sure. Certain sutras contradict, not everyone follows all sutras, and the canonical literature outside of sutras goes every which way.

What we try to do in this sub is to treat Mahayana sutras as authoritative as a general idea; especially the widely accepted ones, moving any heavy conflicts over to Open Dharma. Beyond sutras, Abhidharma and certain masters such as Nagarjuna and Vasubandhu are widely considered authoritative for Mahayana. Any school/tradition specific masters or works are usually redirected to the subforum for the appropriate school, this includes sutras that aren't widely accepted across the spectrum of Mahayana schools in East Asia and Tibet-Nepal-Mongolia.

Tantras are generally considered authoritative over on the Vajrayana sub.

It's not a perfect system, but it's about the best we can do given the situation.

Discussions regarding authoritative texts will always lead to an endless loop of repeating the same arguments. Over at the "western buddhism" group on fb this debate comes up over and over again, the mods intend the group to be pan-buddhist but most times this is not the case. I normally pinch in if I see a too strong opposition to Mahayana sutras, unfortunately by the mods themselves sometimes...
Vegetarianism is one of the topics that come up in this discussions, the bodhisattva vows, the tantric texts (I'm not a tantric practitioner, nor a scholar, and there doesn't seem to be many well versed people on the group that can actually defend them). Topics like this are normally closed with a conclusive "I agree to disagree.. But I'm more right."

There really isn't a solution for this situation.

Then, the Licchavi Vimalakīrti spoke to the elder Śāriputra and the great disciples: “Reverends, eat of the food of the Tathāgata! It is ambrosia perfumed by the great compassion. But do not fix your minds in narrow-minded attitudes, lest you be unable to receive its gift.”

"Butchers, prostitutes, those guilty of the five most heinous crimes, outcasts, the underprivileged: all are utterly the substance of existence and nothing other than total bliss."The Supreme Source - The Kunjed Gyalpo
The Fundamental Tantra of Dzogchen Semde

I agree, but I doubt a realized being would waste his time trying to convince others of the authority of his texts on the internet.

Then, the Licchavi Vimalakīrti spoke to the elder Śāriputra and the great disciples: “Reverends, eat of the food of the Tathāgata! It is ambrosia perfumed by the great compassion. But do not fix your minds in narrow-minded attitudes, lest you be unable to receive its gift.”

I pretty much stick to the Nichiren & East Asian sub-forums for this reason. There does seem to be a divide between Indian/Tibetan Mahayana and East Asian Mahayana. Maybe it’s not as pronounced as it seems on this forum, but at any rate, I don’t think there’s much to be done about it.

As far as taking it as a personal affront when people don’t find certain texts authoritative, I don’t think that’s helpful or charitable. Personally, I’m pretty much only interested in East Asian Mahayana as it pertains to my own practice.

There is actually a large collection of texts from India that are present in both the Chinese and the Tibetan canon, plus the Pali canon - or at least the Sutta Pitaka - is generally regarded as buddhavacana.

What's authoritative in this sub, and what is less authoritative or not at all authoritative?

Whatever scriptures and treatises both parties accept can be used for reference, otherwise there are two valid sources: reasoning and experience.

According to Mahayana Buddhism, the history of Mahayana Buddhist doctrine is a narrative and catalogue of decline.

Whose interpretation of Mahayana is that? The Prajnaparamita and Vaipulya sutras were taught to beings with purer mind than the sravakas, and Tantras are claimed to be taught to those who were even more superior.

Innovations in the teachings are not improvements; they are signs of degeneration

Calling them innovations makes sense only if Mahayana sutras are viewed as historically later works, and that is a very modern view, not the traditional one. Furthermore, taking the historical perspective, later works are usually based on earlier ones, so they should actually be viewed as further extensions at least, not degeneration.

This suggests that the canon of Mahayana texts recorded in Sanskrit, prior to the decline of Buddhism in India, must be more authoritative for the purposes of pan-Mahayana discussion than, say, later Chinese, Tibetan, Japanese, or Korean doctrinal systems.

If it is OK to accept texts that are not the actual teachings of Shakyamuni, i.e. all the Mahayana scriptures, why look down on those composed beyond the Indian cultural sphere?

1Myriad dharmas are only mind.
Mind is unobtainable.
What is there to seek?2If the Buddha-Nature is seen,
there will be no seeing of a nature in any thing.3Neither cultivation nor seated meditation —
this is the pure Chan of Tathagata.4With sudden enlightenment to Tathagata Chan,
the six paramitas and myriad means
are complete within that essence.